TWO-STAGE COMPRESSION DEVICE

摘要

Provided is a two-stage compression device which can adjust an internal compression ratio according to an external compression ratio. A two-stage compression device (1) has a low-stage compression unit (7) and a high-stage compression unit (8) and is configured in such a manner that the shaft of one of the screw rotors (5, 6) of the low-stage compression unit (7) and the high-stage compression unit (8) is connected thereto. A capacity adjustment means (14) is provided to the high-stage compression unit (8), and the volume ratio which is the ratio between a suction volume at the moment when a compression space is isolated from an intermediate flow passage (10) and a discharge volume at the moment when the compression space is connected to a discharge flow passage (11) is changed according to the ratio between the pressure in the intermediate flow passage (10) and the pressure in the discharge flow passage (11) by changing the discharge volume.